Proper land drainage is an important aspect of any structural, landscaping, industrial or residential undertaking. Standing effluent can infiltrate and undermine slabs and other structural foundations. A systematic use of sand, gravel, grading and drainage pipes, familiar to those skilled in the art, are employed to facilitate drainage of effluent, typically rain effluent, away from primary structures. The drainage pipes typically exit onto a street or gutter leading to municipal drainage systems. Since the drain courses through an underground system, there is opportunity for roots, dirt and other debris to be gathered into the pipe system. A simple grate placed at the end of the drain pipe to deter intrusion restricts the flow of effluent and corresponding debris. The accumulation of debris can contribute to a back up of effluent or the cover may be expelled and washed away by heavy effluent flow. Due to problems arising from grating the ends of the pipes and the potential environmental clutter associated with washed out drains, solid grated end covers are seldom used.
In addition to the above technical and functional aspects of proper drainage system design, there are numerous species of animals that can be found in proximity to residential, industrial and other structures. These animals typically require a nesting ground or other safe haven from which they may venture forth in search of food, nesting materials, etc. An unguarded drain pipe at street level provides ideal conditions for any number of small animals, such as reptiles, rodents, amphibians, birds and the like. With the suburban sprawl associated with many areas of the country, large populations of animals are taking refuge in and near residential, commercial and other neighborhoods where they are considered undesirable pests.
Currently there are a number of plastic covers or grates on the market for rainwater drainage. The products are typically of monolithic construction with no moving parts. These grates, if placed over drainage pipe exits, require frequent maintenance due to debris collecting within the pipe. In addition, the flow of effluent is restricted, leading to deposition of debris further inside the pipe and, in some cases, complete blockage by the grate protecting the drain exit from intrusion. For this reason grates are seldom used in practice.
One example of a grate intended to deter intrusion by animals but address the restriction of effluent flow is disclosed in U.S. Pat. No. 5,102,537. It is clear that such a grate will be of limited utility in deterring the wide range of animals that typically colonize drainage systems.
Another device intended to deter intrusion without hindering effluent flow is disclosed in U.S. Pat. No. 4,702,828. This device is similarly of limited utility in deterring the wide range of animals that typically colonize drainage systems.